#include <DB/Storages/MergeTree/AllMergeSelector.h>

#include <cmath>


namespace DB
{

AllMergeSelector::PartsInPartition AllMergeSelector::select(
	const Partitions & partitions,
	const size_t max_total_size_to_merge)
{
	size_t min_partition_size = 0;
	Partitions::const_iterator best_partition;

	for (auto it = partitions.begin(); it != partitions.end(); ++it)
	{
		if (it->size() <= 1)
			continue;

		size_t sum_size = 0;
		for (const auto & part : *it)
			sum_size += part.size;

		if (!min_partition_size || sum_size < min_partition_size)
		{
			min_partition_size = sum_size;
			best_partition = it;
		}
	}

	if (min_partition_size)
		return *best_partition;
	else
		return {};
}

}
